August 21, 2008
Why are Jamaicans so fast? permlink
Category: Genetics
I haven't been watching the Olympics, but my news feeds are broad enough that I get a general sense of who is winning, and who is not. Over at Genetic Future Dan MacArthur has a post up, The gene for Jamaican sprinting success? No, not really:
And Bolt is not the only Jamaican to impress in short distance events in Beijing: the country's women's sprint team took all three medals in their 100 metre dash.
Naturally, these performances have provoked widespread speculation about the basis of Jamaica's sprinting success, and the short-distance prowess of other populations of West African ancestry. One controversial suggestion has drawn the most headlines: that sprinting is in their genes, or rather in one gene in particular - variously referred to as "Actinen A" or "ACTN3".
Posted by Razib at 12:30 AM•2 Comments
August 18, 2008
Atheists and apostates: similarities and differences permlink
Category: Religion
A personal experience of mine is that many apostates from religion have...issues. On the other hand, people who were raised, or always were, atheists tend to mostly be almost confused by religion. But I was curious as to possible differences between these two groups, and those believe in God, or were unbelievers and now believed in God. So I decided to check the GSS. Here's the bottom line for the GODCHNG variable:
64 DON'T BELIEVE NOW, NEVER HAVE
116 DON'T BELIEVE NOW, USED TO
174 BELIEVE NOW, DIDN'T USED TO
2,610 BELIEVE NOW, ALWAYS HAVE
In the tables below you read from left to right, those who are atheists, always were, to those who are atheists, weren't always, those who are theists, weren't always, and those who are theists and were always. Two points
1) I'm surprised at how step-wise some of the trends are. Look at the proportions for sex for example.
2) There are some data which suggest that those who leave religion experience stressed relationships with their family. See the data for time spent with family.
Read on »
Posted by Razib at 6:21 AM•6 Comments
Beware the dark-eyed permlink
Category: Genetics
p-ter points me to a new paper in Trends in Ecology, Pleiotropy in the melanocortin system, coloration and behavioural syndromes:
In vertebrates, melanin-based coloration is often associated with variation in physiological and behavioural traits. We propose that this association stems from pleiotropic effects of the genes regulating the synthesis of brown to black eumelanin. The most important regulators are the melanocortin 1 receptor and its ligands, the melanocortin agonists and the agouti-signalling protein antagonist. On the basis of the physiological and behavioural functions of the melanocortins, we predict five categories of traits correlated with melanin-based coloration. A review of the literature indeed reveals that, as predicted, darker wild vertebrates are more aggressive, sexually active and resistant to stress than lighter individuals. Pleiotropic effects of the melanocortins might thus account for the widespread covariance between melanin-based coloration and other phenotypic traits in vertebrates.
The fact that blondes have more fear and redheads feel more pain might make some more sense. Skin color seems to have gotten lighter over the past 5-20 thousand years across northern Eurasia by substitutions and changes in frequency on a few loci of large effect. Evolutionarily this predicts that pleiotropy will product side effect phenotypes before modifier genes can arise to mask the deleterious byproducts of said evolution.
Posted by Razib at 12:50 AM•5 Comments
August 16, 2008
Insulting religions and races; should it be allowed? permlink
Category: Culture
In the United States we have the free speech built into the law, so it is somewhat a moot point. Of course, as evidenced by comments in many other Western countries the limits to speech are bounded by public consensus. So I decided to look at the GSS in terms of response to one question:
After I read each statement, please tell me if you strongly agree, aggee, neither agree nor disagree, disagree, or strongly disagree with the statement.
a. Under the First Amendment guarnateeing free speech, people should be allowed to express their own opinions even if they are harmful or offensive to members of other religious or racial groups.
Here is what I found....
1) Across politics there doesn't seem to be a strong trend. Extreme liberals do tend to go bimodal where a large minority support speech restriction, but the N is small. Interestingly, moderates are the most open to speech restriction. Perhaps because moderates are the least like to need protection because they're so inoffensive ;-)
2) A very moderate trend while increasing intelligence and free speech absolutism. But far less than I'd expected.
3) A rather noticeable trend toward free speech absolutism from junior college on up in terms of education...but the N for junior college isn't large. It seems actually the trend is weaker than I'd thought it would be here, the less educated aren't that much more open to speech suppression!
4) Little difference across races.
5) Some differences across regions.
I checked a few other variables. There doesn't seem to be much difference. I'm pretty surprised, and happily so! Someone else can check the regression or correlations, but where there are trends the N's are suspiciously small for those categories, so I'm skeptical that there will be many statistically significant differences. The tables are below the fold.
Read on »
Posted by Razib at 10:29 PM•25 Comments
France and nuclear power permlink
Category: Science
France Reaffirms Its Faith in Future of Nuclear Power:
Nuclear power provides 77 percent of France's electricity, according to the government, and relatively few public doubts are expressed in a country with little coal, oil or natural gas.
...
France generates half of its own total energy, up from 23 percent in 1973, despite increased consumption.
Electrical power generation accounts for only 10 percent of France's greenhouse gases, compared with an average of 40 percent in other industrialized countries, according to EDF.
There is No Free Lunch, and life is about trade offs. Those who live in the American Pacific Northwest know this well; hydroelectric power is great and low risk, and results in cheap electricity which helps drive high tech industry such as aerospace and electronics. But, there are ecological downsides.
The key isn't to rely on a silver-bullet energy source which we need faith in. Rather, it's to evaluate and weight the risks and rewards of various technological portfolios. Any given action will have costs, we simply have to judge whether the benefits are worth those costs. As it is, most of the objection nuclear to power seems almost animistic at the root. These sorts of "gut-level" heuristics and biases draw upon the same "wisdom of repugnance" which is wielded against biological engineering and technology, though of course with coalitional politics being what they are different sects, so to speak, emphasize different domains when it comes to unleashing their intuitive aversion.
Note: The sign of the reflexive vector can go in both directions. Today many people have a strong bias against nuclear energy based on a small number of accidents and disasters, while in the 1950s the belief in its ability to free up humanity was almost religious and messianic. Both stances are problematic, and I believe fundamentally not rooted in empiricism as opposed to faith.
Posted by Razib at 8:22 PM•13 Comments
Taking the pill might make your brother hawt? permlink
Category: Genetics
MHC-correlated odour preferences in humans and the use of oral contraceptives:
Previous studies in animals and humans show that genes in the major histocompatibility complex (MHC) influence individual odours and that females often prefer odour of MHC-dissimilar males, perhaps to increase offspring heterozygosity or reduce inbreeding. Women using oral hormonal contraceptives have been reported to have the opposite preference, raising the possibility that oral contraceptives alter female preference towards MHC similarity, with possible fertility costs. Here we test directly whether contraceptive pill use alters odour preferences using a longitudinal design in which women were tested before and after initiating pill use; a control group of non-users were tested with a comparable interval between test sessions. In contrast to some previous studies, there was no significant difference in ratings between odours of MHC-dissimilar and MHC-similar men among women during the follicular cycle phase. However, single women preferred odours of MHC-similar men, while women in relationships preferred odours of MHC-dissimilar men, a result consistent with studies in other species, suggesting that paired females may seek to improve offspring quality through extra-pair partnerships. Across tests, we found a significant preference shift towards MHC similarity associated with pill use, which was not evident in the control group. If odour plays a role in human mate choice, our results suggest that contraceptive pill use could disrupt disassortative mate preferences.
It's Open Access, you can read it yourself. I've gotten a few emails inquiring about this paper, and Darwin Catholic pretty much baited me into posting on this. There's been a fair amount of treatment of the results in the media as well. This isn't the first paper of this kind, there's a large genre of work (copiously referenced above) on the relationship between smell, MHC and female attraction to men. To restate the basic findings here: taking the birth control pill seems to have resulted in a shift of women toward greater preference of those with immune profiles similar to themselves. We already know that women have very strong preferences for individuals of the same race as compared to men, so a follow up on male preferences at some point would be interesting. Perhaps men don't care what a woman smells like?
Read on »
Posted by Razib at 1:45 AM•8 Comments
August 15, 2008
Brain size ∝ rate of evolution? permlink
Category: Genetics
Brain Size and the Diversification of Body Size in Birds:
Large brains are associated with increased cognitive skills, enabling animals to use new environments and resources more successfully. Such behavioral flexibility is theoretically expected to have macroevolutionary consequences. First, populations of big-brained individuals should more easily become established in new locations, increasing opportunities for allopatric speciation and decreasing chances that the species as a whole becomes extinct. Second, the ability to use new resources should place new selection pressures on populations, promoting adaptive diversification, a process termed "behavioral drive." In this article, we show that the average brain size of a bird family explains a significant fraction...of the rate at which body size diversifies within the family. The association is independent of the number of species in the family, geographic range, and correlates of speciosity, providing the first general support for the importance of behavioral drive in evolution.
Here is what ScienceDaily has:
Read on »
Posted by Razib at 6:13 AM•2 Comments
Tropic Thunder permlink
Category: Culture
Ultrabrown has a review of Tropic Thunder. I'm tempted to go see it....
Posted by Razib at 1:27 AM•2 Comments
August 14, 2008
Hardcore neuroscience permlink
Category: Biology
Check it, Kaleidoscopik (work safe).
Posted by Razib at 10:42 PM•0 Comments
Porn has not become mainstream permlink
Category: Culture
According to assman (yes, that's his name), porn has not become mainstream. The post is totally work-safe FYI.
Posted by Razib at 11:55 AM•1 Comments
Keeping up with the literature permlink
Category: Technology
Pubmed + RSS + iGoogle = Easy Lit Updates:
...The idea is to use the combined power of Pubmed, RSS feeds and iGoogle to create a page of RSS feed boxes that will keep you continually updated on articles containing your keywords of interest, or from specific authors or journals. It is nice and simple, but I find it an incredibly powerful and fast method of literature scanning compared to email updates or browsing each journal individually.
Posted by Razib at 11:37 AM•0 Comments
The Genetic Map of Europe permlink
Category: Genetics
The figure above comes from the an article in The New York Times, The Genetic Map of Europe, which draws from a new paper, Correlation between Genetic and Geographic Structure in Europe. The authors sampled 2,500 Europeans across 300,000 points of genetic variation, then extracted out the components of that variation, and plotted the individual data points along the two largest independent dimensions. You note that various samples tend to cluster geographically with each other; i.e., Finns tend to cluster with other Finns, Italians with Italians. This makes sense since Europe hasn't been a random mating population, most people found mates from local regions. Sandman, Genetic Future and Dienekes have extensive comments so I'll leave it at that. But, below the fold I've taken a less stylized figure, which shows all the individuals sampled as points, and added some labels to give you a better geographical intuition.
Read on »
Posted by Razib at 3:50 AM•26 Comments
August 13, 2008
Profile of Reihan Salam permlink
Category: Culture
The Daily Star in Bangladesh has published a profile I wrote of Reihan Salam.
Posted by Razib at 5:40 PM•5 Comments
Vitamin D deficiency → reduced fitness? permlink
Category: Genetics
25-Hydroxyvitamin D Levels and the Risk of Mortality in the General Population:
In cross-sectional multivariate analyses, increasing age, female sex, nonwhite race/ethnicity, diabetes, current smoking, and higher body mass index were all independently associated with higher odds of 25(OH)D deficiency...while greater physical activity, vitamin D supplementation, and nonwinter season were inversely associated. During a median 8.7 years of follow-up, there were 1806 deaths, including 777 from CVD. In multivariate models (adjusted for baseline demographics, season, and traditional and novel CVD risk factors), compared with the highest quartile, being in the lowest quartile...was associated with a 26% increased rate of all-cause mortality...and a population attributable risk of 3.1%. The adjusted models of CVD and cancer mortality revealed a higher risk, which was not statistically significant....
ScienceDaily, Low Vitamin D Levels Pose Large Threat To Health; Overall 26 Percent Increased Risk Of Death. Death due to ateriosclerosis probably isn't the strongest evolutionary force; most people who die of heart disease are past reproductive peak. But, it is noted in this, and other, research that Vitamin D levels seem to have a global influence on fitness, probably mediated through immune robusticity.
Related: Evolution of human skin color.
Posted by Razib at 1:16 PM•6 Comments
August 12, 2008
Open Access Wars, part n permlink
Category: Blog
Reed Elsevier caught copying my content without my permission:
Scientists provide the content for Elsevier's journals. They donate their time to review, and often edit, the articles that appear in the journals. They make up the bulk of the audience for the journals. Yet Elsevier has, time after time, demonstrated a complete lack of respect for scientists and the scientific community. It's not a surprise that they would decide to grab my post, while ignoring my rights to my own material. It's simply another example of where their focus is: intellectual property matters if and only if it's theirs.
As they say, read the whole thing....
Posted by Razib at 7:29 PM•1 Comments
Steve Fuller; in a word, worthless permlink
Category: Evolution
Today I stumbled on to this article in The New York Times, In U.S., Partisan Expert Witnesses Frustrate Many, and thought of Steve Fuller; the sociologist of science who testified for the Creationists at the Dover trial. John points me to this awesome take-down of Fuller's book, Science v. Religion? Intelligent Design and the Problem of Evolution. A nice sample:
Read on »
Posted by Razib at 12:45 AM•2 Comments
